The idea that most successful startup founders are in their twenties is a myth — the average entrepreneur is much older

A study by MIT found that the average age of startup founders is around 42, and the average age of entrepreneurs who founded high-growth companies is 45.

The study also found that 20-something founders have the lowest likelihood of starting a company with a successful exit.

Mark Zuckerberg was 19 when he started Facebook from his Harvard dorm room. Steve Jobs was 21 when he launched Apple Computer from his family's garage. David Karp was 20 when he started his microblogging site Tumblr.

The list of successful, youthful Silicon Valley entrepreneurs is long, and it might seem as though celebrated startup founders are getting younger all the time.

However, it turns out that the idea that most successful startup founders are 20-something entrepreneurs is more of a persistent Silicon Valley myth. Yes, they exist, but statistically it's rare. According to a recent study by MIT, the average age of a successful company founder is much older than you might think. The study, which was conducted by MIT Sloan professor Pierre Azoulay and PhD student Daniel Kim, analyzed 2.7 million people who founded companies between 2007 and 2014.

According to the results, the average age of entrepreneurs who started a company that went on to hire just one employee was 41.9, and the average age of founders who started a high-growth company is even older, at 45 years old.

The study also examined the age of entrepreneurs in sectors like specialized tech employment, venture capital investing, and patent firms, which yielded similar results: The average age of these people, too, was somewhere in their early-to-mid forties.

"Our primary finding is that successful entrepreneurs are middle-aged, not young," the study reads. "Founders in their early 20s have the lowest likelihood of successful exit or creating a 1 in 1,000 top growth firm."